Numerical Simulation Of MFL-testing For Fillet Weld

Welding technique has been widely used in various fields of modern engineering. As the impact of various parameters during welding process,there will be some cracks,pores,slags,and no fusions defects in welding structures inevitably. In order to ensure the welding product quality, all welding structure should be inspected and evaluated effectively. The yoke-magnetization is usually applied in MFL-testing of welds. In this paper, we focus on the yoke-magnetization testing for a fillet weld and analyze the changes in magnetic flux under different situation.Fillet weld is very common in welding structure which usually contains welding defect. But we do not have a good way to inspect fillet weld. Because of the specialty of fillet weld structure and the restriction of testing device, the defect may not be in the location suitably detected, which is normally at the center of yoke poles. And then there will be a distance between magnetized center and defects. The effective magnetized area is reduced and the rate of detect-ability would decline.In this paper, we analyze the MFL-testing of transverse crack on fillet weld using the finite element analysis, focusing on the influence of the distance between the yoke and fillet weld on the magnetic flux leakage density. The computer results show that with the distance increases, the magnetic flux leakage decrease. And also we obtain the decay function of magnetic flux leakage density. The width and depth of cracks as an important parameter has great influence on the distribution of magnetic flux leakage. The computer results show that with the width increases, the magnetic flux leakage decreases. And with the depth increases, the magnetic flux leakage density increases.